Photon-Mediated Phenomena in Semiconductor Nanostructures
(Photon-Mediated Phenomena, HPRN-CT-2002-00298)
Start date: August 01, 2002
Duration: 48 months
Mid-Term Review Report
(August 01, 2002 – July 31, 2004)
Network co-ordinator: Prof Alex L. Ivanov
School of Physics and Astronomy
Cardiff University
Queen’s Buildings
5 The Parade
PO Box 913
Cardiff CF24 3YB
Wales, United Kingdom
Tel: +44 - 2920 - 875315
Fax: +44 – 2920 – 874056
Email: IvanovA@cf.ac.uk
Network home page: http://www.astro.cardiff.ac.uk/research/PMPnetwork/index.html
Location of the mid-term review meeting: School of Physics and Astronomy, Cardiff
University, Conference Room WX/3.14
Date and timing of meeting:
August 31, 2004
Please keep the text of this report to the minimum, using diagrams and tables wherever
possible.
PART A - RESEARCH RESULTS
A.1 Scientific Highlights
We have followed the main scientific aims formulated in our Network project:
Task 1. Optics of QDs embedded in a three-dimensional microcavity
(Lead team: Dortmund)
As we have already discussed in the first annual report, the experiments performed by the
Network YR, Dr N. Le Thomas (Dortmund team), demonstrated the highest coupling
efficiency of spontaneous emission (beta-factor) ever observed for semiconductor
nanocrystals. This result was achieved by replacing spherical, colloidal CdSe nanocrystals by
anisotropic CdSe nanorods. The highly polarized emission couples almost 100% into TEmodes of spherical microcavities while the TM-modes are suppressed. Dr N. Le Thomas also
achieved an optical detection of single CdSe nanorods and analysed the temperaturedependent line shape.
Strong coupling of atoms or semiconductor quantum dots with photons in high-Q
microsphere cavities are in the focus of current investigations. Such systems are discussed e.g.
as sources of deterministic single photons and entangled photons. Semiconductor
nanocrystals, as has been demonstrated in antibunching experiments are possible candidates of
a solid state-based “atom”, however, their optical transition dipole moment was found to be
much smaller with respect to epitaxially grown quantum dots. We studied the impact of
anisotropy and crystal symmetry of semiconductor nanostructures for achieving high optical
transition dipole moments by comparing nanorods and nanodots. Making use of the Bloch
part of the excitonic wave function, i.e. the solid state nature of the “artificial atom”, we are
able to transform the exciton ground state symmetry of a CdSe nanorod from an optically dark
to optically bright states with high degree of linear polarisation. By measuring the photon
lifetime, we show experimentally for R = 3µm spheres with a sufficiently low mode volume V
~ 200(/n)3, the existence of a high quality factor Q > 200 000, which should be allow to
enter the strong coupling regime with emitters of ~3ns-1 spontaneous radiative decay rate. By
attaching the spheres with nanocrystals having a high optical transition dipole moment, the
line shape of some cavity modes exhibit a splitting of ~40 micro eV that we attributed to the
strong coupling regime.
Within “Dortmund-Paderborn” cooperation, in order to develop tuneable, photochemically
stable, and positioned nanoemitters in photonic structures we tested a new epitaxial technique,
the hybrid growth of MBE using nanocrystals as colloidal seeds. The enormous potential of
colloidal nanocrystals concerning tunability shall be combined with device-compatible
techniques of Molecular Beam Epitaxy to grow monolithic, high-Q optical microcavities with
nanocrystals as the active optical material. It is planned to test different nanocrystalline
emitters by integrating them in compact, monolithic microcavities or by embedding them in
micromechanically tuned microcavities with movable 2D-structured mirrors as an alternative
approach. The optical properties we want to control are the positioning of nanoemitters in
field maxima/minima, stable single dot emission, control of polarization degree, minimizing
of decoherence, and transition dipole moment control by wave function engineering. A result
of the above cooperation is a common Dortmund/Paderborn patent application.
1
The Network YR, Dr N. Nikolaev (Cardiff team) develops theoretical optics of single
photonic dots, aiming to share the results with the Dortmund and Lund teams. The Grenoble
team, involving support from other national grants, aims to fabricate solid state single photon
sources based on CdTe and CdSe quantum dots in pillar microcavities. An experimental setup has been developed for quantum optics measurements of these photonic devices at low
temperature (photon correlation, entanglement, interference with two photons, etc.). This
acquired knowledge will be shared with the Network partners.
Task 2. Optical properties and relaxation kinetics of MC polaritons
(Lead team: Grenoble)
The Grenoble team has performed a number of unique experiments on Bose-Einstein
condensation of microcavity (MC) polaritons in CdTe-based nanostructures under
nonresonant optical excitations. The Paderborn team fabricated and characterised some of the
samples. Recently, the Grenoble team has developed a set-up which allows spectroscopic
imaging in real- and k- spaces to investigate the optical properties of microcavity polaritons.
Relaxation of polaritons along the dispersion curve has been studied as a function of the
excitation density using a nonresonant excitation. In the low excitation regime, a marked
bottleneck effect at high in-plane k wavevectors is clearly observed. For higher excitation, it is
suppressed and at a given threshold, the far-field emission pattern consists of a sharply
"speckled" ring. This could be the first observation of spontaneous coherence in a solid state
system (international state-of-the-art). The relevant experimental results obtained recently by
the Dortmund team, deal with the polariton broadening in energy and momentum space
measured as a function of in-plane momentum: when optically exciting the lower polariton
branch, the strong dispersion versus wavevector results in a directional emission on a ring.
The cooperation between the Cardiff and Cambridge teams has resulted in the suggestion
and development of a new field in the optics of semiconductor microcavities – resonant
acousto-optics of MC polaritons. Namely, in contrast with the conventional acousto-optics,
which usually deals with weak, nonresonant acousto-optic nonlinearities due to the
photoelastic effect, the proposed scheme exploits the excitonic states nearly resonant with the
acoustic and optical fields simultaneously. As a result, the large-value, resonant acousto-optic
nonlinearities can be realised. The resonant acousto-optic effect is particularly strong and
well-defined for MC polaritons parametrically driven by a surface acoustic wave (SAW). If
we realize the resonant acousto-optic effect at room temperature (ZnSe- or GaN-based
microcavities) it will probably be a real breakthrough in the device acousto-optics.
The Cambridge team has developed and studied models of coherent exciton condensation
in semiconductor microcavities. A new cooperative work of the Grenoble and Cardiff teams
on the LO-phonon-mediated optical Stark effect for MC polaritons is in progress.
Task 3. Interface-photon-mediated interaction of self-assembled quantum dots (QDs)
(Lead team: Cardiff)
The Cardiff and Dortmund teams have studied, both theoretically and experimentally, the
radiative corrections to the excitonic molecule (XX) state in GaAs-based microcavities. This
work is extremely important for the project, because for the first time we have demonstrated
the co-existence of the MC and interface, QW polaritons and the importance of the “hidden”
optics associated with the evanescent light field of interface polaritons. Namely, we prove that
the radiative corrections to the XX state, the Lamb shift (a real part of the energy) and
radiative width (an imaginary part of the energy), are large, about 10%-30% of the molecule
2
binding energy and definitely cannot be neglected. Furthermore, we demonstrate that the
optics of excitonic molecules is dominated by the in-plane resonant dissociation of the
molecules into outgoing 1-lambda-mode and 0-lambda-mode cavity polaritons. It is the latter
decay channel, which deals with the short-wavelength MC polaritons invisible in standard
optical experiments, that refers to the “hidden” optics of microcavities.
The Cardiff team is currently completing a theoretical study of the interface-photonmediated interaction of self-assembled or surface-deposited QDs (the Network YR, PhD
student C. Creatore is involved in this study). The conventional optics of interface (selfassembled) or surface-deposited (colloidal) quantum dots (QDs) deals with the pump and
signal light associated with bulk photon modes. However, a long-distance coupling between
the dipole-active electronic states (excitons) in QDs also occurs by means of in-plane
propagating interface photons. The interface light is localized in the z-direction (the structure
growth direction) and invisible at macroscopic distances from the nanostructure. Thus the
interface photons contribute to the total optics of in-plane distributed QDs in a “hidden” way.
Thus we develop the interface, quasi-two-dimensional optics and to describe how the QDs
communicate via interface photons. The microscopic approach we use deals with in-plane
randomly-distributed QDs (Poisson statistics) which are inhomogeneously broadened in
energy (Gaussian statistics). The calculated eigen-spectrum of the Hamiltonian “bulk photons
+ QDs” allows us to classify the eigenstates in terms of the rapidly decaying modes (“radiative
states”) and relatively weakly decaying modes (“interface photon-mediated QD states”).
Furthermore, a very particular design of microcavities for the evanescent light field was
proposed and developed. The first experiments on visualization of the interface light field
associated with self-assembled InGaAs QDs have been performed by the Lund team
The Cardiff team also studies analytically and model numerically, partly in cooperation
with the Cambridge team, relaxation and photoluminescence dynamics of long-lived indirect
excitons in GaAs/AlGaAs coupled quantum wells.
Task 4. Disorder and decoherence effects in the optical response of photonic structures
(Lead team: Cambridge)
The Cambridge team currently deals with modelling of the crossover of a coherent polariton
condensate to a semiconductor laser. Pair-breaking processes from non-equilibrium physics
are found to be the dominant reason (rather than temperature or density constraints) for the
suppression of coherence. Prediction of the shape of the angular emission of light from a
coherent condensate of both excitons and separately polaritons in a trap is made. This is
relevant to the emission spectra measured by the Grenoble group. The crossover from
polariton Bose condensation to a coherent condensate driven by photon coupling is analysed.
This establishes the regime where optical coupling is the dominant mechanism, which in
practice covers the physical regime of parameters.
The Cambridge team has also studied the behavior of a system that consists of a photon
mode dipole coupled to a medium of two-level oscillators in a microcavity in the presence of
decoherence. Two types of decoherence processes, which are analogous to magnetic and
nonmagnetic impurities in superconductors, have been analysed. In addition, modelling of
electron and hole transport have been performed for optically-excited coupled quantum wells.
The Cardiff and Cambridge teams have also started a theoretical study on disorder-induced
change of the wavevector-frequency boundary between the interface and bulk photon modes
resonantly coupled with QW excitons.
Work of the Cambridge team on coherent excitons in microcavities is directly in response
to experiments of Grenoble and Dortmund groups. Using real and k space imaging the
3
Grenoble team has obtained the first evidence of localized polaritons in semiconductor
microcavities (international state-of-the-art). The localization energy amounts to about 1 meV.
A clear spectral blueshift can be observed with increasing excitation density, most probably as
a result of Coulomb interaction between localized carriers.
Task 5. Spectroscopic methods for detection of interface light
(Lead team: Lund)
The Lund team has recently investigated random telegraph noise (RTN) in individual InP
quantum dots in GaInP where the photoluminescence is modulated and discovered a new type
of noise. The "old" type of RTN consisted of a modulation of the intensity of the
photoluminescence. The newly discovered noise consists of a shift of the emission lines
without any change of the total emission intensity. The Lund group has also developed a
comprehensive theory of which correlation functions can occur for electrons and also for
bosons. This is important for the calculation of few-particle effects in quantum dots and
quantum wires. Furthermore the Lund team has investigated the effect of etching on
individual quantum dots where clear effects of strain relief have been observed when the
capping layer is removed from the dots. The strain effects on capped quantum wires have been
studied where the capping layer strains the core of the wire. These studies have been perfomed
on level of individual quantum wires (consisting of a GaAs core and a GaInP shell). All the
above research works directly relate to the experimental search for the interface light field
associated with excitons in QDs, QWells and QWires (see Task 3). The latter experiments are
still in progress. Currently, the Lund group is particularly concentrated on the observation of
the exciton-mediated interface light field and fast diffusions of excitons in quantum wires.
Future plans involve more investigations of the possibility of finding an exciton crystal in a
quantum wire, which has been predicted by A.L. Ivanov in 1993.
The Lund team has observed that the emission lines from single InP quantum dots shift
with temperature, where the shift is dependent on the energy position of the lines in a
systematic way. The Lund team has also calculated the basic electronic structure of most III-V
quantum dots grown on most III-V substrates, as outlined in Task 5. In addition the team has
etched out dots in predefined places in pillars. The magnetic field effects and the formation of
Landau levels in individual InP quantum dots are planned to be investigated within “LundGrenoble” cooperation.
Task 6. Materials Characterisation
(Lead team: Crete)
The Paderborn team has grown and sent to FORTH for Cross-section Transmission Electron
Microscopy (XTEM) three quantum dot samples (#1031, 1035, 1036) prepared by a StranskiKrastanow process, during the period of Dr H. Ouacha (a Network YR, Crete team)
secondment to Paderborn. These growths are part of the activities planned within Task 7
(Paderborn team) while the analyses are part of the activities within Task 6. The highlight of
these results: (a) The QDs were formed in all the specimens. However the best well defined
dots were observed in the specimen 1036, (b) The QDs were not periodic laterally or along the
growth, (c) Extended defects were not observed between the QDs and the matrix, and (d) In
the specimen 1035, ZnSe areas have the hexagonal structure.
In addition, the Crete group will perform a high-precision XTEM characterization of
structures with self-assembled GaInAs QDs for the optical experiments of the Cardiff team on
the long-distance photon-mediated interaction of QDs.
4
Task 7. Formation principles of II-IV Quantum Dots in microcavities
(Lead team: Paderborn)
The main scientific result of the Paderborn team was the deveplopment and MBE-preparation
of ZnSe-based microcavities with CdZnSe-Multi-Quantum Wells, which have shown large
Rabi-splitting at room temperature. We have demonstrated for the first time that polariton
devices, based on II-VI microcavities, can potentially operate at room temperature (normal)
conditions. The optimisation of the Bragg mirror processing was the most crucial pre-request
to achieve this result extremely important for possible technological applications. The samples
were optically characterized by the Grenoble group. The YR N.Rousseau is fully integrated
into this research work. In collaboration with the Crete-Team cross-section Transmission
Electron Microscopy (XTEM) studies have been performed, to understand in more detail the
formation kinetics of self-organized grown CdSe quantum dots. In these experiments Dr. H.
Ouacha (a Network YR, Crete team) was directly involved in the MBE sample preparation.
The results of these experiments allow us to integrate CdSe-QD-layers in ZnSe-microcavity
structures, according to the working plan.
In turn, the Grenoble team, using a new MBE process, has succeeded in obtaining a clear
Stranski-Krastanov growth mode for self-assembled CdTe and CdSe QDs. For both types of
QDs, no thermal activation of confined carriers is observed up to 150-200K. The Grenoble
group has also developed the technology for a hybrid microcavity based on dielectric mirrors
and ZnSe-based microcavities grown on GaAs substrates. This know-how will be shared with
Network partners.
Some preliminary work on room-temperature polaritons in ZnSe-based microcavities
parametrically driven by a surface acoustic wave is planned within “Paderborn-Cardiff”
collaboration, in order to study the resonant acousto-optic effect proposed by the Cardiff and
Canbridge teams.
As detailed above and discussed in Subsection B.3 (Breakdown of Tasks and Milestones), our
PMP Network project has definitely already advanced the international state-of-the-art.
A.2 Joint Publications and Patents
List of the PMP-Network publications
[1] N. Le Thomas, E. Herz, O. Schöps, and U. Woggon, “Spectroscopy of single CdSe
nanorods: Fine structure and polarization properties”, submitted to Physical Review Letters.
[2] N. Le Thomas, O. Schöps, B. Möller, U. Woggon, and M.V. Artemyev, “Spectroscopy of
single CdSe nanorods”, Technical digest of CLEO/IQCE, Mai 2004 San Francisco, USA.
[3] U. Woggon, R. Wannemacher, M.V. Artemyev, B. Möller, N. Le Thomas, V. Anikeyev,
and O. Schöps, “Dot-in-a-dot: electronic and photonic confinement in all three dimensions”,
Applied Physics B: Lasers and Optics 77, 469 (2003).
[4] B.M. Möller, U. Woggon, M.V. Artemyev, and R. Wannemacher, “Photonic molecules
doped with semiconductor nanocrystals”, Phys. Rev. B, in press (2004).
5
[5] W. Langbein, P. Borri, U. Woggon, V. Stavarache, D. Reuter, and A. D. Wieck,
“Radiatively limited dephasing in InAs quantum dots”, Phys. Rev. B 70, 033301 (2004).
[6] P. Borri, W. Langbein, U. Woggon, M. Schwab, M. Bayer, S. Fafard, Z. Wasilewski, and
P. Hawrylak, “Exciton dephasing in quantum dot molecules”, Phys. Rev. Lett. 91, 264701
(2003).
[7] P. Borri, W. Langbein, U. Woggon, A. Esser, J.R. Jensen, and J.M. Hvam, “Biexcitons in
semiconductor microcavities”, Semicond. Sci. Technol. 18, S351 (2003).
[8] B. Möller, U. Woggon, M. V. Artemyev, and R. Wannemacher, “Mode control by
nanoengineering light emitters in spherical microcavities”, Appl. Phys. Lett. 83, 2686 (2003).
[9] S. Schneider, P. Borri, W. Langbein, U. Woggon, J. Förstner, A. Knorr, R. L. Sellin, D.
Ouyang, and D. Bimberg, “Self-Induced transparency in InGaAs quantum dot waveguides”,
Appl. Phys. Lett. 83, 3668 (2003).
[10] W. Langbein, “Spontaneous parametric scattering of microcavity polaritons in
momentum space”, submitted to Phys. Rev. B.
[11] A. Kudelski, K. Kowalik, J. Kasprzak, A. Golnik, J.A. Gaj, T. Wojtowicz, and G.
Cywiński, “Magnetic field controlled in-plane optical anisotropy in parabolic (Cd,Mn,Mg)Te
quantum wells”, Phys. Stat. Sol. (c), in press (2004).
[12] M Richard, J Kasprzak, R Andre, L S Dang, and R Romestain “Consequences of strong
coupling between excitons and microcavity leaky modes”, to be submitted to Applied Physics
Letters.
[13] A. Smith, N. I. Nikolaev, and A. L. Ivanov, "Coherent optics of spherical photonic dots:
weak and strong coupling regimes", Proceedings of the 27th International Conference on the
Physics of Semiconductors 26th-30th July 2004 Flagstaff, Arizona, USA.
[14] F. M. Marchetti, B. D. Simons, and P. B. Littlewood, “Condensation of Cavity Polaritons
in a Disordered Environment”, submitted to Phys. Rev. B, cond-mat/0405259.
[15] M. H. Szymanska, P. B. Littlewood, and B. D. Simons, “Polariton condensation and
lasing in optical microcavities – the decoherence driven crossover”, Phys. Rev. A 68, 013818
(2003).
[16] J. Keeling, P. R. Eastham, M. H. Szymanska, and P. B. Littlewood, “Polariton
condensation with localised excitons and propagating photons”, submitted, condmat/0407076.
[17] P. R. Eastham, M. H. Szymanska, and P. B. Littlewood, “Phase locking in quantum and
classical oscillators: polariton condensates, lasers, and arrays of Josephson junctions”,
submitted, cond-mat/0306268.
[18] Mats-Erik Pistol, “N-representability of correlation functions and density matrices”,
submitted to Phys. Rev. B, cond-mat/0406300.
6
[19] J. Persson, U. Hakansson, M-.E.Pistol, W. Seifert, and L. Samuelson, “Strain effects on
InP quantum dots”, submitted and probably accepted now to Phys. Rev. B.
[20] N. Panev, M.-E. Pistol, W. Seifert, and L. Samuelson, “Random telegraph noise in small
InP quantum dots”, accepted to Phys. Rev. B.
[21] Mats-Erik Pistol, “A new quantum Zeno effect”, to be submitted to Science before end of
August.
[22] G. Kiriakidis, N. Katsarakis, K. Moschovis, E. Gagaoudakis, M. Suchea, S.
Christoulakis, and M. Katharakis, “InOx Thin Film Gas Sensor“ (“Aισθητήρας αερίων από
λεπτά υμένια InOx”), 20th Panhellenic Conference on Solid State Physics & Materials
Science (ΧΧ ΠΣΣΥ), Ioannina – Greece, September 26-29, 2004, submitted (in Greek).
[23] N. Katsarakis, K. Moschovis, E. Gagaoudakis, M. Suchea, S. Christoulakis, M.
Katharakis, and G. Kiriakidis, “Conductivity Change of InOx Thin Films in function of
thickness and UV Exposure” (“Μεταβολή Αγωγιμότητας Υμενίων InOx Συναρτήσει του
Πάχους και της Έκθεσης σε UV”), 20th Panhellenic Conference on Solid State Physics &
Materials Science (ΧΧ ΠΣΣΥ), Ioannina – Greece, September 26-29, 2004, submitted (in
Greek).
[24] M. Katharakis, S. Christoulakis, N. Katsarakis, M. Koudoumas, M. Suchea, K. Savvakis,
T. Efthimiopoulos, and G. Kiriakidis, “Surface ZnO Microstructures manufactured by PLD
method” (“Επιφανειακές Μικροδομές ZnO με τη μέθοδο PLD”), 20th Panhellenic Conference
on Solid State Physics & Materials Science (ΧΧ ΠΣΣΥ), Ioannina – Greece, September 2629, 2004, submitted (in Greek).
[25] M. Suchea and G. Kiriakidis, “Correlation of Surface Characteristics of In and Zn Oxides
by AFM”, CAS International Conference, Sinaia, Romania, October 4-6, 2004, contributed
paper, submitted.
[26] G.Kiriakidis, N.Katsarakis, M.Katharakis, and M.Suchea, “Ultra Sensitive Low
Temperature Metal Oxide Gas Sensors”, CAS International Conference, Sinaia, Romania,
October 4-6, 2004, invited paper, submitted.
[27] A. Pawlis, O. Husberg, A. Kharchenko, K. Lischka, and D. Schikora, “Structural and
optical investigations of ZnSe based semiconductor microcavity structures”, Phys. Stat. Sol.
(a) 188, 983 (2001).
[28] A. Pawlis, A. Kharchenko, O. Husberg, D. J. As, K. Lischka, and D. Schikora, “Large
room temperature Rabi-splitting in a ZnSe/(Zn,Cd)Se semiconductor microcavity structure”,
Solid State Commun. 123, 235 (2002).
[29] A. Pawlis, A. Kharchenko, O. Husberg, D. J. As, K. Lischka, and D. Schikora, “Large
room temperature Rabi-splitting in II-VI semiconductor microcavity quantum structures”,
Microelec. Journal. 34, 439 (2003).
7
[30] A. Pawlis, D. J. As, D. Schikora, J. Schörmann, and K. Lischka, “Photonic devices based
on wide gap semiconductors for room temperature polariton generation”, (invited paper),
submitted to Phys. Stat. Sol. (2004).
Special issue of Journal of Physics: Condensed Matter, Vol. 16 (08 September 2004; for
details see http://www.iop.org/EJ/journal/-page=forthart/0953-8984/1)
[31] P. B. Littlewood, P. R. Eastham, J. M. J. Keeling, F. M. Marchetti, B. D. Simons, and M.
H. Szymanska, “Models of coherent exciton condensation”, pp S3597-S3620.
[32] A. L. Ivanov, “Thermalization and photoluminescence dynamics of indirect excitons at
low bath temperatures”, pp S3629-S3644.
[33] W. Langbein, “Energy and momentum broadening of planar microcavity polaritons
measured by resonant light scattering”, pp S3645-S3652.
[34] M. Richard, J. Kasprzak, R. Andre, L. S. Dang, and R. Romestain, “Angle resolved
spectroscopy of polariton stimulation under non-resonant excitation in CdTe II-VI
microcavity”, pp S3683-S3688.
[35] A. Pawlis, A. Kharchenko, O. Husberg, K. Lischka, and D. Schikora, “Preparation and
properties of ZnSe/(Zn,Cd)Se multi quantum well microcavities for room temperature
polariton emission”, pp S3689-S3694.
[36] N. I. Nikolaev, A. Smith, and A. L. Ivanov, “Polariton optics of semiconductor photonic
dots: weak and strong coupling limits”, pp S3703-S3720.
[37] M.-E. Pistol, “InP quantum dots in GaInP”, pp S3737-S3748.
[38] S. Osborne, P. Blood, P. Smowton, Y. C. Xin, A. Stintz, D. Huffaker, and L. F. Lester
“Optical absorption cross section of quantum dots”, pp S3749-S3756.
[39] G. Kiriakidis and N. Katsarakis, “Photon sensitive high-index metal oxides films”,
S3757-S3768.
PMP Network joint publications (for abstracts, see the annex):
[40] A.L.Ivanov, P.Borri, W. Langbein, and U. Woggon, “Radiative corrections to the
excitonic molecule state in GaAs microcavities”, Phys. Rev. B 69, 075312 (2004).
[41] A. L. Ivanov and P. B. Littlewood, “Resonant acousto-optics of microcavity polaritons”,
Semiconductor Science and Technology 18, S248 (2003).
PMP Network Patent:
[42] M.V. Artemyev, E. Herz, K. Lischke, D. Schikora, and U. Woggon, “Verfahren zur
Integration von kolloidal erzeugten Nanopartikeln in epitaktische Schichten”, DE 10 2004 008
065.8, February 19, 2004.
8
Conference Presentations of PMP-Network Young Researchers
“Micro-Photoluminescence of single CdSe nanorods”,
N. Le Thomas, E. Herz, M.V. Artemyev, and U. Woggon, Quantum Dot 2004 Banff/Canada , 9-14
May 2004.
“CdSe doped Micro-Spheres: Candidates for a Thresholdless Laser”,
N. Le Thomas, O. Schöps, M.V. Artemyev, and U. Woggon, 304th WE-Heraeus-Seminar (Elementary
Quantum-Processors) , 13-15 October 2003.
“Engineering of Exciton-Photon Coupling in micro-spheres”,
N. Le Thomas, E. Herz, M.V. Artemyev, and U. Woggon, International Workshop on Solid State
Based Quantum Information Processing QIP 2004, 2004, Herrsching, Bavaria, 13 rd-17th September
2004.
“Low-temperature spectroscopy of single CdSe nanorods: Fine structure and polarization
properties”,
N. Le Thomas, E. Herz, O. Schöps, M.V. Artemyev, W. Langbein, and U. Woggon, MRS meeting,
Boston, 29th-3rd December.
“Nanocrysal-doped polymer spheres as building blocks for coupled resonator optical waveguides”,
B. Möller, N. Le Thomas, M.V. Artemyev, and U. Woggon, MRS meeting, Boston, 29th-3rd
December.
“Shape-control of the optical selection rules in CdSe nanorods”,
O. Schöps, E. Herz, B. Möller, N. Le Thomas, M.V. Artemyev, and U. Woggon, MRS meeting,
Boston, 29th-3rd December.
N. Le Thomas, “Optical Parameters of CdSe Doped Microspheres”, 1st PMP Network in Cardiff ,
28th-31st March 2003.
N. Le Thomas, “Optical Properties of Spherical Micro-resonators and CdSe Nanocrystals”, 2nd PMP
Network, Crete, 24th-25th October 2003.
A. Kudelski, O. Krebs, J. Kasprzak, G. Cywiński, P. Voisin, and J.A. Gaj, “Giant in plane optical
anisotropy induced by longitudinal magnetic Cd1-xMnxTe”, International Conference on Physics of
Semiconductors, Edinburgh 2002, oral presentation.
10th International Conference on Shallow-Level Centers in Semiconductors, Warsaw 2002, attended
by Jacek Kasprzak.
J. Siwiec-Matuszyk, J. Kasprzak, A. Babinski, and M. Baj, “Intersubband scattering in
pseudomorphic GaAs/InGaAs/AlGaAs structure”, XXXI International School of Semiconducting
Compounds, Jaszowiec 2002, poster presentation.
J. Kasprzak, M. Richard, Le Si Dang, R.Romestain, R. Andre, and J.A. Gaj “Polariton effects in II-VI
semiconductor microcavities”, VIII Workshop on Physics of Semimagnetic Semiconductors, Obory
2003, oral presentation.
9
J. Kasprzak, M. Richard, Le Si Dang, R.Romestain, R. Andre, and J.A. Gaj “Stimulation phenemena
in II-VI semiconductor microcavities”, XXXII International School on the Physics of Semiconducting
Compounds, Jaszowiec 2003, poster presentation.
F. Boeuf, M. Miller, M. Richard, R. Andre, J. Bleuse, Le Si Dang, and J. Kaprzak, R. Romestain,
“Polariton Laser: contribution of CdTe based microcavities”, Les Houches 2003 summmer school,
poster presentation.
M. Richard, J. Kasprzak, R. André, Le Si Dang, and R. Romestain, “Angle resolved spectroscopy of
polariton stimulation under non resonant excitation in CdTe II-VI microcavity”, Photon Mediated
Phenomena Workshop.
A. Balocchi, “ZnCdSe/ZnSe strongly coupled microcavities”, 1st Photon Mediated Phenomena
Network Workshop, Cardiff 2003.
A. Balocchi, “Oxide mirrors for blue and infrared microcavities”, 2nd Photon Mediated Phenomena
Network Workshop, Crete 2003.
“International Summer School on Functional Nanostructures” (Karlsruhe, Germany) September 2003,
poster presented by Celestino Creatore.
“SIOE, Semiconductor and Integrated OptoElectronics” (Cardiff, Wales) April 2004, oral presentation
by Celestino Creatore.
“2004 Lectures in Chemistry and Physics: The Nanotechnology Revolution” organized by the
“Onassis Foundation” (Greece) July 2004, attended by Celestino Creatore.
ICTP Winter School on QMC methods (International Centre for Theoretical Physics, Trieste, Italy)
attended by Pablo López Ríos.
“Summer-School on Semiconductor Quantum Dots: Physics and Devices”, Monte Veritá , Ascona
(Italy), 5-10 September 2004 attended by Zeila Zanolli.
Greek Lessons for foreigners, medium level in Philology Department of Crete University, OctoberDecember 2002, attended by Mirela Petruţa Şuchea.
Master on Microelectronics/Optoelectronics - Special Open course: "Semiconductor based
microsensors" by Dr. Vincent Mosser (Schlumberger-France),
May 26 –30, 2003, Physics Department of Crete University, attended by Mirela Petruţa Şuchea.
M. Suchea and G. Kiriakidis, “Atomic Force Microscopy Analysis of Polycrystalline Indium Oxide
Thin films”, poster presented in XIX National Conference in Solid State and Material Science,
Tessaloniki Greece,21-24 September 2003.
International NATO Conference, Hersonissos, Crete, Greece, September 2003, attended by Mirela
Petruţa Şuchea.
3-rd GenLAC Program Meeting, Herssonisos, Crete, Greece, June 1-2, 2004, attended by Mirela
Petruţa Şuchea.
Onassis Lectures 2004: The 2004 Lectures in Chemistry and Physics:
“The Nanotechnology Revolution”, Heraklion, Crete, Greece, July 19-23, 2004, attended by Mirela
Petruţa Şuchea.
10
20th Panhellenic Conference on Solid State Physics & Materials Science (ΧΧ ΠΣΣΥ), Ioannina –
Greece, September 26-29, 2004, attended by Mirela Petruţa Şuchea.
CAS International Conference, Sinaia, Romania, October 4-6, 2004, attended by Mirela Petruţa
Şuchea.
All the young researchers usually attend our regular (bi-annual) Network meetings.
PART B - COMPARISON WITH THE PROJECT PROGRAMME
B.1 Research Objectives
State whether the research objectives, as set down in the project programme of
contract, are still relevant and achievable. If not, explain why.
All the research objectives formulated in Annex I of our Network research programme (see
also our website) are still relevant and achievable. Furthermore, a solid progress has already
been achieved in solving the planned research and training tasks.
B.2 Methodological Approach and Work Plan
Has the methodological approach changed from that described in the contract? If so,
how? Using charts and diagrams only, illustrate how the joint programme of work is
broken down into tasks and which teams are involved in each task. Explain any
significant differences from the work plan envisaged in the contract.
The methodological approach of the PMP-Network has not been changed in comparison with
that detailed in our initial proposal. The research programme is also broken down into the
seven tasks according to our original plan. See the relevant webpage of our website:
http://www.astro.cardiff.ac.uk/research/PMPnetwork/network/projectobj.htm
B.3 Schedule and Milestones
The PMP-Network schedule is consistent with that we put in our original proposal. The
research works, training programme, Network meetings and workshops proceed according to
the initial plan.
Breakdown of tasks and Milestones:
1. The experimental demonstration of the highest coupling efficiency of spontaneous
emission (beta-factor) ever observed for semiconductor nanocrystals. The first realisation
of the strong coupling regime for CdSe nanorods embedded in a spherical microcavity; the
Q-factor of about 200 000 was achieved.
11
2. The unique experiments on Bose-Einstein condensation of MC polaritons in CdTe-based
nanostructures under nonresonant optical excitations.
3. New real-/k-space and resonant Rayleigh spectroscopies of semiconductor microcavities.
As a result, discovery of “polariton rings” in both CdTe-based and GaAs-based MCs.
4. The new epitaxial technique, the hybrid growth of MBE using nanocrystals as colloidal
seeds.
5. The mean-field (macroscopic) and first-principle (microscopic) theories of the long-range
interface-photon-mediated interaction of self-assembled or surface-deposited QDs. Hidden
optics associated with in-plane distributed QDs.
6. The suggestion and development of a new field in the optics of semiconductor
microcavities – resonant acousto-optics of MC polaritons.
7. The unique optical experiments with InP QDs in predefined places on the top of nanopillars.
8. The models of polariton condensation and lasing in optical microcavities.
9. The microscopic theory of decoherence of single-mode MC polaritons.
10. The theoretical models of relaxation kinetics and diffusion of statistically-degenerate
electrons, holes and indirect excitons in coupled QW.
11. The first observation of the MC polariton effects at room temperature (ZnSe-based
microcavities).
12. The radiative corrections to the excitonic molecule state in (GaAs-based) microcavities
have been for the first time calculated and measured.
13. The theoretical investigation of the single-mode excitonic polaritons in photonic dots:
intrinsic transition between the strong and weak coupling regimes.
14. The high-precision XTEM technique for characterization and selection of nanostructures.
15. The discovery of new RTN in photoluminescence of InP QDs.
B.4 Research Effort of the Participants
The research effort of the Network teams is described in detail in the Sections A.1 (Scientific
Highlights), B.3 (Schedule and Milestones), B.6 (Network Organisation and Management)
and Part C (Training). The collaborative research links are schematically shown in the chart
placed below. There are no significant variations with the initial PMP-Network plan.
B.5 Cohesion with Less Favoured Regions
Are any of the network partners from less favoured regions of the community? If so,
explain the efforts that have been made to integrate them into the project.
The Crete team, which is from EC Less Favoured Regions, has a very important role in the
PMP-Network: it is responsible for characterization and selection of various photonic nanostructures provided by other Network-teams (Paderborn and Cardiff). By putting the Cardiff
12
team to coordinate the Network, we strongly promote Welsh physics, in particular, optoelectronics, to the best of European standards.
B.6 Network Organisation and Management
The PMP Network organisation and management exactly follow our initial approach and are
detailed at our Network website:
http://www.astro.cardiff.ac.uk/research/PMPnetwork/index.html (see also the schematic).
Schematic of the PMP Network structure and management.
Major Network meetings and workshops
(1) An introductory meeting of the Network lead members took place at Cardiff in May 2002,
just before the start date of the project. We have discussed the Network research tasks, our
future cooperations and the relevant organising questions. Prof Leonid V. Keldysh (Physics
Institute, RAS, Moscow), an internationally leading expert in semiconductor physics, attended
the meeting and contributed a lot to the discussions of the scientific programme.
13
(2) The first working meeting “Photon-Mediated Phenomena – 1st Network Conference”
(28.03-31.03.2003, Gregynog, Wales) was organised by the Cardiff team, according to the
Workplan. Apart from the Network members, many leading experts in semiconductor optics
have contributed to the meeting by giving overview talks and by participating in various
Network-related discussions: Profs H. Akiyama (ISSP, Tokyo University), K. Cho (Osaka
University), S.-L. Chuang (University of Illinois), A. Kavokin (LASMEA, France), L. Levitov
(MIT, USA), M. S. Skolnick (University of Sheffield), D. Snoke (University of Pittsburgh,
USA), S. G. Tikhodeev (General Institute of Physics, RAS, Moscow), V. B. Timofeev (ISSP,
RAS, Chernogolovka), and Drs F. Laussy and I. Shelykh (LASMEA, France). All together, 43
participants attended the meeting. The conference was very successful, and the Proceedings
will be published in a special issue of Journal of Physics: Condensed Matter. The details of
the meeting (its program, list of participants etc.) are on our web site.
(3) The second working meeting “Photon-Mediated Phenomena – 2st Network Conference”
was organized by the Crete team, according to the Workplan, and took place at Hersonissos,
Crete, October 24-25, 2003. All the groups were represented (about 20 attendees) and an
overall number of thirteen contributed talks were presented both by senior members of the
groups as well as by YRs (for details see the Network website). The meeting generally rated as
very successful, was rounded up by an extensive discussion coordinated by Prof. A. L. Ivanov
covering issues related to current scientific progress and achievements as well as plans for
further strengthening collaborative work and exchange activities.
(4) The Mid-Term-Review Meeting of the PMP Network is planned to be at Cardiff, on
August 31, 2004. Over 25 participants, including all the senior and young researchers of the
Network, an EU RTN scientific officer (Dr. R. Bilyalov), external scientific expert (Prof. K.
Cho, Japan), pro-VC of Cardiff University (Prof. P. Blood), are going to attend this important
meeting.
(5) The forthcoming Third and FourthWorkshops, organised by Detlef Schikora and Ulrike
Woggon, will be held in Paderborn (conference part) and Dortmund (training part) from
October 4th through to October 7th, 2004 (for details visit the Network website).
B.7 Connections to Industry
Describe the involvement of industry in the network. List all companies that have had
a meaningful interaction with the network, explaining in each case the nature of that
interaction (information exchange, participation in meetings, involvement in the
training programme, possible exploitation of results ...). Explain any significant
changes in the involvement of industry from that foreseen in the contract.
There is one PMP-Network patent, filed by the Dortmund and Paderborn teams. The Lund
team has been contacted by Lund-i-Nova, which works on an industrial fabricating of modular
electronics, as a combination of embedded processors and software. Lund-i-Nova and the
Lund team will together develop software and image recognition modules for infrared
imaging. This hinges on if the joint application by Lund/Lund-i-Nova gets granted.
The resonant acousto-optics of excitons and MC polaritons, proposed by the Cardiff and
Cambridge teams, can result in a new generation of effective acousto-optical elements. Such
devices can potentially lead to a new high-tech industry in the EU. We plan to work in this
direction during the last two years of the PMP-Network period.
14
PART C - TRAINING
C.1 Employment of Young Researchers
In a table similar to that below, summarise the number of young researchers (in manmonths) whose employment has so far been financed by the contract and compare it
with the overall deliverable specified in the contract.
Participant
Contract deliverable of Young
Researchers to be financed by the
contract (person- months)
Young Researchers financed by the
contract so far (person-months)
Pre-doc
(a)
Post-doc
(b)
Total
(a+b)
Pre-doc
( c)
Post-doc
(d)
Total
(c+d)
Cardiff
36
30
66
18
18.5
36.5
Cambridge
36
24
60
10
1
11
Grenoble
36
12
48
10
12
22
Paderborn
18
18
36
0
7
7
Dortmund
0
36
36
0
20
20
Crete
0
24
24
18
8
26
Lund
0
24
24
0
12
12
126
168
294
56
78.5
134.5
TOTAL
Explain any cases where the rate of employing young researchers is falling well below
what is expected under the contract. Explain, in particular, in such cases how the
vacancies have been published.
The Network positions were widely advertised via Tip-Top, DFG and Network web sites as
well as through network of collaborating institutes all over Europe sending e-mails and
distributing the existence of vacancies in local and international meetings. We got a lot of
applications (more than two hundred). The appointment of YRs within the PMP-Network
is now nearly completed (the only one vacant position we still have – 18 month pre-doc in
the Paderborn team).
15
C.2 Training Programme
There has been a solid integration of young researchers into our Network. In particular, the
first and second Network meetings (Gregynog, March 2003 and Hersonnisos, October 2003)
have provided the YRs with excellent overview talks, done by the internationally leading
experts in the field of semiconductor optics, on the research subjects. The YRs of the Cardiff
team are involved in a special set of lectures on quantum solid state theory. Mr C. Creatore
(pre-doc, Cardiff team) has attended a one-week summer school on functional nanostructures
(Bad Herrenalb, Germany). YRs C. Creatore (Cardiff) and M. Suchea (Crete) are attending
one week summer school “2004 Lectures in Chemistry and Physics: The Nanotechnology
Revolution” organized by the “Onassis Foundation” in July 2004. Pablo L Rios (YR of the
Cambridge team) has participated in the work of the ICTP Winter School on QMC methods
(International Centre for Theoretical Physics, Trieste, Italy, winter 2003/2004). In order to be
integrated better into the Crete team, M. Suchea (YR of the Crete team) attended Greek
Lessons for foreigners, medium level at Philology Department of Crete University, Special
Open course: "Semiconductor based microsensors" at Physics Department of Crete University
and International NATO Conference, Hersonissos (Crete, September 2003). She also attends
regular graduate level classes offered by the Physics Department of the University of Crete.
Zeila Zanolli (YR of the Lund team) was a student of “Summer-School on Semiconductor
Quantum Dots: Physics and Devices”, Monte Veritá, Ascona (Italy, September 2004). She is
presently being trained in operating and setting up an infrared micro-PL setup. She will soon
also be trained in measurements of individual quantum dots and quantum wires.
Dr N. Nikolaev (post-doc YR, Cardiff team) contributes to supervision of A. Smith, a
research student in Cardiff. The Dortmund team has involved Dr N. Le Thomas into the
training in experiments on micro-PL and time-resolved PL, led by Dr W. Langbein. Prof U.
Woggon gave an extended introduction to published literature concerning optics of
microspheres and spectroscopy of QDs. Dr N. Le Thomas is involved in supervision of
research students. He has also attended the 304 Hereaus-School on elementary quantum
processors (Bonn, Germany). The young researcher of the Lund team (Dr M. Cazayouz) was
introduced into the research area by learning micro-photoluminescence, electron beam
lithography, and etching techniques to isolate individual quantum dots. In the Crete team both
post and pre-doc YRs have had the chance to get an in-depth training on thin film growth
techniques utilizing conventional evaporation and sputtering systems, while they got an
individual training on specific characterization techniques. Dr H. Ouacha was trained on
optical techniques utilizing a VIS/UV spectrophotometer for the study of the film absorption
edges, while Ms M. Suchea got trained on surface topography technique utilizing atomic force
microscopy. Dr H Ouacha was also trained by the Paderborn group (Dr. D. Schikora) in the
epitaxy and optical characterization of Quantum Dot structures.
Secondments: In June 2003, Dr. Hassan Ouacha (Crete team) made a secondment to the
Paderborn team. Three more secondments of YRs are planned for September/October 2004:
Dr. Z. Zanolli (Lund team) to Cardiff, Dr. S. Kos (Cambridge team) to Grenoble, and Mr. C.
Creatore ( Cardiff team) to Lund.
C.3 Factual Information on the Young Researchers
For each young researcher appointed with network funds, provide the following
information in tabular form: name, nationality, age at time of appointment, start and
16
likely end date of appointment, category of researcher (post-doc, pre-doc mentioning
if undertaking PhD studies), scientific speciality, place of work, country of work, and
whether the researcher had previously worked or studied at another network partner.
Currently, there are two female young researchers in the PMP Network: Dr Zeila Zanolli
(Lund team) and Ms Mirela Suchea (Crete team).
Dortmund team
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Nicolas Le Thomas
French
28
December 2002 – December 2004
Post-doc
Optoelectronics
Dortmund Universität
Germany
PhD in Grenoble Team
Grenoble team
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Jacek Kasprzak
Polish
24
01.10.2003-30.09.2006
Pre-doc
Optics and physics of semiconductor
nanostructures
Laboratorie de Spectrometrie Physique
Grenoble
France
No
17
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Andrea Balocchi
Italian
29
1 March 2003 - 29 February 2004
Post-doc
Spectroscopy and dielectric material
deposition
University Joseph Fourier, Grenoble
France
Never worked in a network before
Cardiff team
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Celestino Creatore
Italian
26
01 February 2003-01 February 2006
Pre-doc
Physicist
School of Physics and Astronomy, Cardiff
University, Cardiff, Wales
United Kingdom
No
Nikolay Nikolaev
Bulgarian
33
15 January 2003 – 15 July 2005
Post-doc
Physicist
School of Physics and Astronomy, Cardiff
University, Cardiff, Wales
United Kingdom
No. I had only individual Marie Curie
fellowship – contract HPMF-CT-2000-00499
18
Cambridge team
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Simon Kos
Czech
32
29 June 2004- 28 June 2006
Post-doc
condensed matter theory
Cambridge University
UK
never worked in an EU network.
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Pablo Lopez Rios
Spanish
24
1 October 2003 –30 September 2006
pre-doc
Physicist
Cavendish Laboratory, Cambridge
UK
No
Lund team
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Zeila Zanolli
Italian
29
15 March 2004 – end of the Network
Post-doc
quantum optics, nanostructures
Lund
Sweden
No
19
Crete team
Name
Mirela Petruţa Şuchea
Nationality
Age at time of appointment
Work period in the network
Romanian
29
1-st of Aug 2002-31Dec2002; 1-st of June
2003-present
Pre-doc
Physics
Institute of Electronic Structure and Laser,
Foundation for Research & TechnologyHellas, PO Box 1527, Vasilika Vouton,
71110 Heraklion, Crete
Greece
In the period January-June 2003 I worked in
the “PICNIC” Project with the same location,
Institute of Electronic Structure and Laser,
Foundation for Research & TechnologyHellas, PO Box 1527, Vasilika Vouton,
71110 Heraklion, Crete, Greece.
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Paderborn team
Name
Nationality
Age at time of appointment
Work period in the network
Category of researcher
Scientific speciality
Place of work
Country of work
Whether the researcher had previously
worked or studied at another network partner
Nicolas Rousseau
French
29
12-01-04 - 12-01-05
Post-Doc
Molecular beam epitaxy
Low scale Surface Analysis
Paderborn
Germany
Work within the Renibel EU network
But with allocation from the French state
20
PART D - SKETCHES OF THE YOUNG RESEARCHERS
D.1
For each of the young researchers who will present their experiences at the Mid-Term
Review Meeting, provide a maximum 25 line description of the young researcher’s
scientific background, of his responsibilities in the network and of his experiences
(positive and negative) to date. These sketches should be written by the young
researchers themselves.
Dortmund team
Dr. Nicolas Le Thomas
Before to starting as a post-doc in the PMP network, I made a PhD about the design,
the processing and the optical characterization of semiconductor tunable laser diodes. It was
an applied subject. My scientific background relies mainly on simple optical spectroscopy
experiments (photoluminescence, electroluminescence, photocurrent, and absorption) and
semiconductor device modelling.
During my post-doc in the PMP network, I have been carrying out an experimental
work in the experimental physic group of professor Woggon in Dortmund, Germany. This
work gives me the possibility to extend my fields of expertise to advanced optical
spectroscopy measurements like micro-photoluminescence and time resolved imaging. The
project topic is the study of the coupling between CdSe/ZnS nanocrystals and electromagnetic
modes of spherical micro-cavities. The main motivation is the observation of the strong
coupling regime between a confined electron-hole pair and a photonic mode (photonic
dot/quantum dot coupling).
It is very exciting for me to work in an international laboratory such as the one in
Dortmund. I strongly believe that my competencies have increased a lot. The job fits very
well with what I expected at the beginning of this post-doc. I also enjoy a lot the PMP network
meetings which give the opportunity to present and discuss preliminary results. Moreover
these meetings contributed to develop ideas and to build up fruitful collaborations with other
experimentalist members of the PMP network, as for instance with the Lund team, in order to
make challenging experiments. The main difficulty to carry out such experiments was my
limited contract time.
Grenoble team
Mr. Jacek Kasprzak
I am at the first year of my PhD work in Laboratorie de Spéctrométrie Physique in
Grenoble at Joseph Fourier University. I work under supervision of Dr. Le Si Dang. Our team
is involved in Photon Mediated Phenomena European Research Network. Personally, I take a
part in it as the young researcher, and my work is supported by the means of this program. I'd
like to present some of my experience of being a network member. I have three kinds of
general remarks concerning:
- Scientific contribution of the network,
21
- Quotidian work in laboratory and live in Grenoble
- Financial support.
SCIENTIFIC CONTRIBUTION
The subject of my work is polariton phenomena in microcavities. Being the network
member gives me the unique chance to present my scientific results at network's meetings at
much larger circle then the laboratory. At the same time the regularity of workshops forces me
to recapitulate my results and trains my ability of presentation. The meetings give me fantastic
occasions to meet European scientific community working on the similar subjects: discuss
with experts and other young researchers as well, in informal atmosphere. On the other hand
the network meetings sketch the overview of actual state of work on photon mediated
phenomena in semiconductors on European arena. The meetings give also opportunity to visit
external scientific centres.
LIVE IN GRENOBLE and WORK IN LABORATORY
Decision of starting the PhD work in Grenoble opened a new chapter in my life.
Beside of obvious scientific reasons I was appealed by the beauty of the whole Grenoble
region. Living in Grenoble give me unrepeatable chance to develop my hobbies: mountain
trekking and skiing.
I have a pleasure to work in Laboratory de Spéctrométrie Physique: laboratory with good
tradition and great ambiance. I experience atmosphere of "taking care of the others" every day.
Among many colleges, I have met here a few people, whom now I consider as the friends. I
could find here the people who helped me - as a foreigner who knew neither the language nor
administration – with all: starting from inscription to the university and tons of administration
papers, ending at renting the apartment. I appreciate also the conditions I was employed: I
have the work contract with Joseph Fourier University and I'm PhD student at the same time
(with all the students rights). As a member of "équipe mixte UJF-CEA-CNRS” I have a
possibility to cooperate with strong grenoblan scientific community.
FINANCIAL SUPPORT
The financial support I am given is enough to live in Grenoble, even if these are the
means for me and my wife. I find it very good that there are the money to cover my journey to
Poland - my homeland, once a year. I am also grateful for paying for me two months of French
courses.
Dr. Andrea Balocchi
Before the appointment I completed a PhD at the Physics department at Heriot-Watt
University, Edinburgh, Scotland. The subject of the research has been the development of a
fibre-based tunable semiconductor VCSEL for and telecommunications spectroscopic
purposes. The research has mainly involved the design and actual realisation of the device and
its subsequent characterisation. In addition, the PhD research has involved the spectroscopic
characterisation of wide band-gap II-Vi materials (ZnSe, ZnS, MgS, MgSe and alloys) grown
in the group for the realisation of room-temperature strongly coupled devices.
The work during the year as network post-doc has involved the design and realisation of
highly reflecting dielectric Bragg mirror for visible and UV strongly coupled microcavities.
The work has included the investigation of the suitable materials for the wavelength of
interest and the most appropriate method of deposition for the minimisation of absorption and
material roughness.
22
During the year I have also contributed in the spectroscopic research on the materials and
structure developed in the group and in particular on the cathode-luminescence of wide bandgap materials such as ZnO and GaN.
The position as network post-doc has allowed me on one side to broaden my spectroscopic
knowledge. I have learned new technique and methods of optical investigation of
semiconductors. In addition the use of different instrumentation has widen my technical
experience in this domain.
Moreover, the work on the dielectric material deposition has allowed exploring and varying
my knowledge towards field on which during my PhD I was only indirectly involved.
The network has allowed me to exchange experiences and knowledge especially with
the group of Paderborn.
During my appointment as network post-doc I participated to two network organized
meetings:
1st March 2003 in Cardiff:
“ZnCdSe/ZnSe strongly coupled microcavities”
2nd October 2004 in Crete:
“Oxide mirrors for blue and infrared microcavities”
Cardiff team
Mr. Celestino Creatore
I graduated in Italy in October 2002. I got my degree after a four years study course
and a one-year project. My research concerned the application of unsupervised-learning
algorithms (derived in a statistical mechanics framework) applied to magnetoencephalographic signals. The research was developed within the Theory Group of the
Physics Department and the neuroscientists of the “FateBeneFratelli” Hospital in Rome.
Since February 2003 I am a Young Researcher Ph.D. student within the “Photon
Mediated Phenomena Network” project and I work at the Department of Physics and
Astronomy in Cardiff University, under the supervision of Prof. Ivanov.
My present research investigates the interaction between photons and Quantum Dots. Briefly,
it is a theoretical work (both analytics and numeric have being developed) which in the near
future will be developed in collaboration with other researchers joining the Network, in
particular, the group of Dr. Pistol (Lund Team, Sweden) for experimental work and the group
of Prof. Littlewood (Cambridge Team, U.K) for theory.
As a young researcher within the Network I think that the importance of the meetings
with the other members is huge and it enriches the Ph.D. work: it is a great opportunity to
have a useful exchange of ideas in a friendly and informal atmosphere. Besides the scientific
work, I have been involved in the organization of the first meeting of the network (held in
Cardiff on April 2003) and the technical preparation of the proceedings.
Besides the Network meetings, I have attended and presented a poster at the
“International Summer School on Functional Nanostructures” (Karlsruhe, Germany) on
September 2003, attended and had an oral presentation at the International Conference “SIOE,
Semiconductor and Integrated OptoElectronics” (Cardiff, Wales) on April 2004, attended
(with a fellowship) the “2004 Lectures in Chemistry and Physics: The Nanotechnology
Revolution” organized by the “Onassis Foundation” in Greece on July 2004.
Dr. Nikolay Nikolaev
23
My name is Nikolay I. Nikolaev. I was born in Svishtov, Bulgaria, in 1970. I received
my MSc degree in 1993 in the Department of Quantum Electronics and Laser Physics of Sofia
University. In 1999 he received his Ph.D. degree in the area of electromagnetic wave
propagation at the Department of General Physics of Sofia University. From 1997 through to
2000 I worked as researcher and scientific collaborator in Institute of Electronics, Bulgarian
Academy of Science. From 2000 through to 2001 as a assistant professor in the Department
of Physics, University of Architecture, Civil Engineering and Geodesy in Sofia. From 2001
through to 2003 I worked as a PostDoc researcher at Fraunhofer IISB in Erlangen, Germany
under Marie Curie Individual Fellowship. On 15.01.2003 I became a member of PhotonMediated Phenomena Network and I started work as a research associate in the Department of
Physics and Astronomy of Cardiff University in Wales, UK. My previous research experience
and interests - investigating and modelling of wave propagation in different media –
gyrotropic plasma, nano-semiconductor structures fit well to the research activities of the
network. I have a desire to mention the benefits for me as a member of network:
-Due to the financial support of the network I can continue evolving of my research career.
For me is also important that I work here in Cardiff among many highly qualified scientists in
the Physics department. Attending of various seminars (some of them funded by network) is
useful for me.
-Financial support of the network for buying necessary for science computer systems,
software, books.
-The benefit for me is supervision of my work from Prof. Ivanov. The often scientific
discussions with him and his big scientific experience and scientific contacts with many
outstanding scientists are great help for me.
-Another advantage of being member of network is the possibility for the scientific contacts
between our group here in Cardiff and another teams from our Network. The scientific
meetings (Gregynog, Crete, Cardiff), information exchange via Internet, telephone provide
good base for improvement of my scientific work.
For my stay here I have one article which will be published very soon in Journal of Physics:
Condensed Matter. Now I am preparing a next paper. We plan to submit it to Phys. Rev. B.
-I took part in preparation of scientific meeting in Gregynog.
-I took part in preparation of the special issue of Journal of Physics: Condensed Matter
containing the Proceedings of the First Workshop of the Network in Gregynog.
-I work as a second supervisor of the PhD student Andrew Smith.
Cambridge team
Dr. Simon Kos
As a PhD student at the University of Illinois in Urbana, I worked on various problems
in superconductivity using the quasiclassical approximation both in the Andreev and in the
Eilenberger formalism. As a postdoc in Los Alamos, NM, I first studied the Ce-based 115
heavy-fermion materials, thus joining a major experiment-theory effort there at that time.
Specifically, I helped analyze the NMR and specific-heat data on the material to show that
they both suggested a two-component description of the material. I then worked on energy
transfer between quantum-well and quantum-dot excitations, and on spin dynamics, both
involving inorganic semiconductors. In Cambridge, I would like to extend these last studies
into conjugated organic materials. I am new to Cambridge as well as to the Network; I expect
to learn about my responsibilities in the network at the Meeting.
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Mr. Pablo López Ríos
The problem in which I have started to work is finding the theoretical phase diagram
of the homogeneous electron-hole system, which is a model for semiconductors described by
a small number of parameters. Knowledge of the theoretical properties of the system for given
values of these parameters shall serve as a guide for experimentalists and engineers in their
use and development of materials and devices.
The numerical tool of choice in this area is the Quantum Monte Carlo (QMC) method,
as it has been proven capable of performing many-body integrals without omitting correlation
effects, thus yielding the most accurate results currently available. Cambridge QMC code is
called Casino, which aims at being a completely general, flexible package capable of treating
systems ranging from atoms to complex molecules and solids, using some of the best-known
QMC methods: Variational Monte Carlo (VMC), correlated-sampling Variance Minimization
(VM) for VMC wave-function optimization, and fixed-node Diffusion Monte Carlo (DMC),
which is extremely powerful.
In this first year of my PhD studies, I've become familiar with the QMC method as
well as with the Casino program. Some of the contributions I've made to this project so far
are: inclusion of an automatic time step optimization algorithm for VMC; correlation-time
calculation routines; optimization of existing VM algorithms, achieving performance
increases of up to 300%; a small number of contributions to the package's script library, and
general debugging. For the specific case of electron-hole systems, we have developed a new
functional form of the wave-function that we hope shall shed light on some inconsistencies
found in previous theoretical studies of the phase diagram. This has also been implemented in
Casino, and the preliminary results obtained for the two-dimensional electron-hole bilayer one of the systems of interest- do look promising.
There is still work to be done in order to draw a well-characterized phase diagram of
the electron-hole system, but it seems to me that the basis is now set and accurate results will
follow in a short time.
Lund team
Dr. Zeila Zanolli
Scientific background:
I’ve conducted a PhD research activity on GaAs-based Quantum Cascade Lasers
(QCLs) and LEDs emitting in the midbased on inter-subband transitions in a multiple quantum well heterostructure, so their
emission wavelength can be chosen by design. The study was developed across the various
design issues (comparing different injector and active region schemes, designing new devices
and calculating the appropriate waveguide layers), the optimization of the fabrication
techniques and of the whole processing scheme of the lasers, and the optical and electrical
characterization of the devices. These measurements were performed at low temperature
(10K) using an FT-IR spectrometer operated both in step-scan and in rapid-scan mode.
I have theoretical experience in the QM study of the time evolution and decoherence
effects in two level systems due to the interactions with the external environment.
Responsibilities in the network and experiences (positive and negative):
25
Our group is working to build a new setup for detecting infrared (1photoluminescence from quantum dots. We have planned to study InP and InAs quantum dots
embedded in (Ga)InP and (Al)GaAs quantum wires, respectively.
My activity was mainly devoted to writing a labVIEW program to control the whole
experimental setup. This program allows the control of the spectrograph (grating, wavelength
and entrance slit width selection), of the IR camera and of the DT3157 frame grabber for the
different image acquisition modes of the camera.
The image acquisition part of the program was the most challenging one, since at the
beginning even the DT sample programs were not working. Work was done to understand the
right settings of both camera and frame grabber to make them working together. Besides the
frame grabber was supposed from DT Company to be controlled via a Visual C++ program,
so the calling of the DT functions was made via the “Call Library Function” mode of
labVIEW.
Crete team
Dr. Mirela Şuchea
Scientific background
I studied physics in Physics Faculty at the University of Bucharest (1991-1997) with
Biophysics Specialization in the 4th and 5th years of study. I am licensed in Physics–
Biophysics with the License work: “The Ultrasonography. An Application in the PressureVolume Relation Study of the Left Ventricle”(1999), Coordinating teacher: Lect. Dr. Puiu
Bălan. In 1999 I attended the lectures in Consultant School for medical equipment at Zepter
Romania, Bio-Vita Program. In 2001 I got E. U. attestation as Medical Consultant for
Bioptron A.G. Switzerland. Between April 2000 and July 2002 I was working like assistant
laboratory in RAMI-Dacia –Synthetically Diamond Factory, Bucharest Romania. From
September 2002-present I am also a masters student in the Microelectronics Department of
Crete University.
Work experience
My main training work consists of structural and morphological characterization of
surfaces by microscopy and in particular utilizing, optical, AFM and SEM as well as TEM and
XTEM. I have followed lectures and sort time practical work in XRD, spectroscopy (UV-VIS,
FTIR and photoluminescence), optical and electrical characterizations, Hall measurements,
and IC’s processing work at the Laboratories at FORTH.
Working as a young researcher in the Crete team I learned also thin films growth techniques
utilizing the conventional evaporation and dc magnetron sputtering techniques.
Paderborn team
Dr. Nicolas Rousseau
I have joined the Photon mediated phenomena network as a post-doctoral the 12 of
January 2004. During the first time, I have been trained on various methods of semiconductor
characterizations. Specifically, I have acquire new understanding on high resolution X ray
diffraction, cathode-luminescence, reflection high energy electron diffraction, atomic force
spectroscopy, Energy Dispersive X-ray Analysis. Also, I have drastically improved my skills
26
in crystal growth techniques. I am now able to master the growth of GaAs layers,
heterostructures based on ZnSe, ZnMgSe, ZnCdSe, CdSe, and I equally get a strong knowhow
on the growth of Stranski-Krastanov CdSe quantum Dots. This knowledge will be now
helpful to realized planar microcavities with CdSe quantum well or stacked CdSe quantum
dots as active layers.
After this training period, I have start a work on Bragg mirror based on ZnSe and
ZnMgSe layers. My aim with this study, is to obtain an high reflectivity (above 90%) centered
on 520 nm, which is the exact wavelength of the active layer inside microcavities. Concerning
this work, I have already cross many steps. In order, the mastering of the magnesium content
inside the ZnSe layers, and also a perfect control of layers thicknesses, which is a crucial
parameter for positioning the stop band of the mirror. So this two first results allow us to
produce in a reproducible way Bragg-mirrors centered on 520 nm with a reflectivity of more
than 80%.
Now, my work will consist in improving the reflectivity to reach 90% and be able to realize a
microcavity with a backside Bragg mirror ZnMgSe/MgSe. I would like to add the fact that
this work is realized in cooperation of a PhD student (M.Arens) which works also on it.
PART E - NETWORK FINANCING
E.1
Compare, in tabular form, the expenditure to date of each network partner (an
estimate will be sufficient) with the allowable costs foreseen in the table following the
signatures in the contract. Also estimate a breakdown of the total expenditure to date
by the network into the cost categories A, B, C and D. Explain any substantial
differences from the rates of spending originally foreseen.
The PMP Network expenditure will be reported to the EU Commission directly by the RACD
(Cardiff University) responsible for the Network budget: Mr Nick Bodycombe (Email:
BodycombeN@Cardiff.ac.uk) and Ms Cerys Thomas (Email: ThomasCE5@Cardiff.ac.uk).
However, they can prepare the Mid-Term PMP-Network financing report in the very
beginning of August 2004 only.
PART F - PROPOSED REVISION TO THE CONTRACT
F.1
If the co-ordinator considers that any revisions may be necessary to the contract,
particularly to its project programme, these should be outlined, with explanations
where they have not already been given earlier.
There is no need to revise the PMP Network contract.
27
ANNEX. Abstracts of joint publications.
A.L. Ivanov, P. Borri, W. Langbein, and U. Woggon, “Radiative corrections to the
excitonic molecule state in GaAs microcavities”, Phys. Rev. B 69, 075312 (2004).
Abstract
The optical properties of excitonic molecules (XXs) in GaAs-based quantum well
microcavities (MCs) are studied, both theoretically and experimentally. We show that
MC
the radiative corrections to the XX state, the Lamb shift  XX and radiative width
MC

XX
, are large, about 10-30% of the molecule binding energy XX , and definitely
cannot be neglected. The optics of excitonic molecules is dominated by the in-plane
resonant dissociation of the molecules into outgoing 1λ-mode and 0λ-mode cavity
polaritons. The later decay channel, “excitonic molecule ? 0λ -mode polariton + 0λ mode polariton”, deals with the short-wavelength MC polaritons invisible in standard
optical experiments, i.e., refers to “hidden optics” of microcavities. By using transient
four-wave mixing and pump-probe spectroscopies, we infer that the radiative width,
associated with excitonic molecules of the binding energy  XX  0.9  1.1 meV , is
 XXMC  0 .2  0 .3 meV
 QW  0.1 meV
in the microcavities and XX
in a reference GaAs
single quantum well (QW). We show that for our high-quality quasi-two-dimensional
nanostructures the T2 = 2 T1 limit, relevant to the XX states, holds at temperatures
below 10K, and that the bipolariton model of excitonic molecules explains
quantitatively and self-consistently the measured XX radiative widths. A nearly factor
MC
QW
two difference between XX and  XX is attributed to a larger number of the XX
optical decay channels in microcavities in comparison with those in single QWs. We
also find and characterize two critical points in the dependence of the radiative
corrections against the microcavity detuning, and propose to use the critical points for
high-precision measurements of the molecule binding energy and microcavity Rabi
splitting.
A.L.Ivanov and P.B.Littlewood, “Resonant acousto-optics of microcavity polaritons”,
Semiconductor Science and Technology 18, S248 (2003).
Abstract
We propose and analyze theoretically a resonant acousto-optic Stark effect for
microcavity (MC) polaritons parametrically driven by a surface acoustic wave. For
GaAs-based microcavities our scheme ``acoustic pumping - optical probing'' deals
with surface acoustic waves of frequency νSAW ˜ 0.5-3 GHz and intensity ISAW˜ 0.1 –
10 mW/mm2. The acoustically-induced stop gaps in the MC polariton spectrum
drastically change the optical response of MC polaritons. Because an acoustically
pumped intrinsic semiconductor microcavity remains in its ground electronic state, no
many-body effects screen and weaken the resonant acousto-optic Stark effect. In the
meantime, this allows us to work out an exactly-solvable model for resonant acoustooptics of MC polaritons which deals with giant acousto-optical nonlinearities. Finally,
we discuss possible applications of the proposed resonant acoustic Stark effect for
optical modulation and switching and describe an acousto-optic device based on a
(GaAs) microcavity driven by a surface acoustic wave.
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